Final answer:
Bivalve mollusks are filter-feeders that draw in water through an incurrent siphon and trap food particles with their gills, which are then transported to the mouth for digestion.
Step-by-step explanation:
Bivalve mollusks, such as clams, oysters, and mussels, have evolved a different feeding mechanism from other mollusks as they lack a radula. Instead, they are filter-feeders and consume food by filtering water. The water enters through an incurrent siphon, passes over gills (also known as ctenidia), where food particles are trapped in mucus and then transported by cilia to the mouth. These particles are then directed into the stomach for digestion. The process of extracting food from water is efficient and allows bivalves to secure nourishment from the surrounding environment without the need for a radula.